I was wondering if it's possible to write Firefox extension using .Net Framework? Had anybody such experience in writing Firefox extensions using C# programming language? Any good sites or guidelines would be very helpful. ![FFPlugin][1] [1]: http://img81.imageshack.us/img81/3049/ffplugin.jpg Here is an example of what I need. Extension to enter phone number and to send SMS Message. I draw it in Paint, so I'm sorry for having no artistic touch.